fix: [2.5] Fix bug for gis function to filter geometry (#44968)

issue: #44961
master pr: #44966 

This PR fixes 3 geometry related bugs:
1. Implement ToString interface for GisFunctionFilter.
2. Ignore GisFunctionFilter MoveCursor for growing segment.
3. Don't skip null geometry for building R-Tree index, should be record
in null_offsets.

---------

Signed-off-by: Cai Zhang <[email protected]>

Author: xiaocai2333

internal/core/src/exec/expression/GISFunctionFilterExpr.h

@@ -54,6 +54,19 @@ class PhyGISFunctionFilterExpr : public SegmentExpr {
         return expr_->column_;
     }
 
+    std::string
+    ToString() const {
+        return fmt::format("{}", expr_->ToString());
+    }
+
+    void
+    MoveCursor() {
+        if (segment_->type() == SegmentType::Sealed) {
+            SegmentExpr::MoveCursor();
+        }
+    }
+
+
  private:
     VectorPtr
     EvalForIndexSegment();

internal/core/src/segcore/FieldIndexing.cpp

@@ -576,16 +576,14 @@ ScalarFieldIndexing<T>::process_geometry_data(int64_t reserved_offset,
                 // Use the accessor to get geometry data and validity
                 auto [wkb_data, is_valid] = accessor(i);
 
-                if (is_valid) {
-                    try {
-                        rtree_index->AddGeometry(wkb_data, global_offset);
-                        added_count++;
-                    } catch (std::exception& error) {
-                        PanicInfo(UnexpectedError,
-                                  "Failed to add geometry at offset {}: {}",
-                                  global_offset,
-                                  error.what());
-                    }
+                try {
+                    rtree_index->AddGeometry(wkb_data, global_offset);
+                    added_count++;
+                } catch (std::exception& error) {
+                    PanicInfo(UnexpectedError,
+                              "Failed to add geometry at offset {}: {}",
+                              global_offset,
+                              error.what());
                 }
             }